Column unit for chair

ABSTRACT

The present invention relates to a column unit for a chair, wherein the column unit for a chair is compact and can improve durability against lateral forces. The present invention relates to a column unit for a chair, in which the height thereof is controlled by upward and downward movements of a spindle assembly, wherein the column unit comprises: an outer pipe comprising an inclined portion of which the diameter gradually becomes larger as it approaches a front end thereof; an inner pipe which is inserted into the outer pipe to form a space portion between the inclined portion and the inner pipe; and a spindle guide which is inserted into the inner pipe to guide the upward and downward movements of the spindle assembly.

This application is the U.S. national phase of International Application No. PCT/KR2012/003187 filed 25 Apr. 2012 which designated the U.S. and claims priority to KR 10-2011-0040989 filed 29 Apr. 2011, the entire contents of each of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a column unit for a chair in which an inclined part of an outer pipe is directly secured to a chair base to provide a good appearance and diversify design of the chair, and more particularly to a column unit for a chair which has a compact configuration and can improve the durability against a lateral force applied to an axis thereof.

2. Description of the Prior Art

As generally known in the art, a gas cylinder is applied to a height control device of a chair. The gas cylinder, as shown in FIGS. 1 a and 1 b, includes an outer pipe 5; a spindle assembly 2 inserted within the outer pipe 5 and moved upward or downward when a gas fluid passage of a valve 8 b is changed, in which the exposed end portion of a piston rod 6 provided within the outer pipe 5 is secured to the bottom surface of the outer pipe 5; and a spindle guide 4 provided within the upper side of the outer pipe 5 for guiding and supporting the upward or downward movement of the spindle assembly 2.

Operation of the gas cylinder constructed above is as follows. If a button (not shown) is pressed to operate a gas open/close pin 8 connected with the valve 8 b, the gas fluid passage of the valve 8 b is opened. At this time, the gas stored within the spindle assembly 2 is introduced through the fluid passage 2 a of the valve to push a piston 5 a. Hence, the spindle assembly 2 is then raised to move a seating plate of the chair upward. When the button is released at a certain position of the seating plate being moved, the fluid passage 2 a of the valve 8 b is closed to maintain the fixed state of the seating plate.

Meanwhile, when the gas cylinder as mentioned above is not applied to the conventional chair but to a special-type chair having a relatively high position which is popular recently, the thickness of the spindle guide 10, i.e., the outer diameter of the spindle guide 10 is further increased as shown in FIG. 2 in order to support the spindle assembly more stably. Here, the upper diameter of the outer pipe 20 is increased. Accordingly, a tapered part L and a linear part T are formed in a certain length at the upper portion of the outer pipe 20, respectively, and then the linear part T is designed to support the spindle guide 10.

However, as to the conventional gas cylinder with these constructions, there may be a case in which the upper linear part T of the outer pipe 20 has to be shorter depending upon a user's need. At this moment, if the linear part T is less than a certain length, the linear part T cannot support the spindle guide 10, which has drawbacks in that the spindle guide 10 is derailed when using the gas cylinder.

As shown in FIGS. 1 a and 1 b, a gas open/close pin 8, a tapered holder 8 a, a valve 8 b and a fluid passage 2 a are provided within the spindle assembly 2 in the same manner. A spindle guide 4 is inserted within the outer pipe 5, and a piston 5 a, a piston rod 6, a cushion cover 6 a and a bearing assembly 6 b may be installed in the outer pipe 5.

Meanwhile, the conventional column unit for the chair has a construction in which the spindle guide 4 is installed in the outer pipe 5 with an upper wide part and a lower narrow part, and the spindle assembly 2 is installed along the inner surface of the spindle guide 4. Here, the spindle guide 4 is secured to the outer pipe 5 through a securing pin 7 (or a spring pin).

Recently, a gas cylinder with a simple design in its appearance has been preferred, and an outer pipe has a tapered shape from its upper end portion in order to render a stable feeling in its appearance as well as a simple design, in which the outer pipe of the gas cylinder is almost abutted to the base of the chair.

However, the conventional column unit for the chair has drawbacks in that when the user seated in the chair moves forward, rearward, leftward or rightward (at 360° in any direction) as shown in FIG. 1 b, a bending moment is repetitively applied to the column unit, so that the spindle guide 4 connected with the outer pipe through the securing pin 7 is gradually derailed with a lapse of time, thereby disengaging the outer pipe 5 from being fixed.

In other words, there are drawbacks in that when the chair has been used for a long period of time, while the user seated in the chair moves forward, rearward, leftward or rightward, the bending moment due to a lateral force has been continuously applied so as to raise (push upward) the spindle guide 4 along the upper part of the outer pipe 5, thereby remarkably degrading the durability of the column unit for the chair.

Cited reference 1: Korean Patent Registration No. 10-0687222

Cited reference 2: Korean Patent Registration No. 10-0477072

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a column unit for a chair which can construct the column unit with a compact configuration and improve the durability against a lateral force, which refers to a horizontal load applied at 360° in any direction with respect to a vertical axis of the column unit.

In accordance with one embodiment of the present invention to accomplish this object, there is provided a column unit for a chair to adjust a height of the chair by moving a spindle assembly upward or downward within the column unit, the column unit including: a cylindrical outer pipe; a piston rod inserted within the outer pipe so as to provide a gas fluid passage of a valve within the outer pipe, the piston rod having an exposed end portion fixed to a bottom surface of the outer pipe; the spindle assembly being moved upward or downward when the gas fluid passage is changed by the piston rod; a spindle guide provided within an upper side of the outer pipe to guide and support an upward or downward movement of the spindle assembly; and an inner pipe inserted within the outer pipe to define a space between an inclined part of the outer pipe and the inner pipe, wherein the outer pipe has a gradually increasing diameter toward an end portion of the outer pipe so that the outer pipe has the inclined part, and the spindle guide is inserted within the inner pipe to guide the upward or downward movement of the spindle assembly.

In accordance with another embodiment of the present invention, there is provided a column unit for a chair to adjust a height of the chair by moving a spindle assembly upward or downward within the column unit, the column unit including: a cylindrical outer pipe; a piston rod inserted within the outer pipe so as to provide a gas fluid passage of a valve within the outer pipe, the piston rod having an exposed end portion fixed to a bottom surface of the outer pipe; and the spindle assembly being moved upward or downward when the gas fluid passage is changed by the piston rod; a spindle guide provided within an upper side of the outer pipe to guide and support an upward or downward movement of the spindle assembly, wherein the outer pipe has a gradually increasing diameter toward an end portion of the outer pipe so that the outer pipe has the inclined part, and the outer pipe is integrally formed with a securing part being curved at its end portion to encompass the end outer peripheral surface of the spindle guide.

The outer pipe may have a linear part extending by a predetermined length from the inclined part.

The outer pipe is formed with an engagement jaw inside of its end portion, and the end portion of the inner pipe is curved outward to be rested on the engagement jaw. The outer and inner pipes may be secured to each other by pressing their outer surfaces.

The inner pipe may be provided with at least one through hole along the outer periphery of its end portion.

The inner pipe may be formed with an engagement protrusion on its inside, and the spindle guide is formed with an engagement recess on its outside into which the engagement protrusion is inserted.

In accordance with still another embodiment of the present invention, there is provided a column unit for a chair to adjust the height of the chair by moving a spindle assembly upward or downward within the column unit, which includes a cylindrical outer pipe, a spindle assembly inserted within the outer pipe and moved upward or downward when the gas fluid passage of a valve is changed in which the exposed end portion of a piston rod provided in the outer pipe is secured to the bottom surface of the outer pipe, and a spindle guide provided within the upper side of the outer pipe for guiding and supporting an upward or downward movement of the spindle assembly, wherein the outer pipe is formed with an inclined part having a gradually increasing diameter toward its end portion, and wherein the outer pipe is integrally formed with a securing part being curved at its end portion to encompass the end outer peripheral surface of the spindle guide.

The spindle guide may be formed with at least one engagement step on its outer peripheral surface.

The spindle guide may have a seating part circumferentially formed at an upper end portion of the spindle guide, the securing part of the outer pipe being seated in the seating part and the seating part being fixed to the securing part while being engaged with the securing part.

Accordingly, the present invention has effects in that the inner and outer pipes are secured to each other by pressing themselves, so as to improve an installation performance, thereby enhancing production efficiency. Moreover, the spindle guide and the inner pipe maintain a parallel and intimately contacted state to uniformly accommodate the load transversely applied thereto, thereby increasing the durability of the device.

In addition, according to the present invention, it has effects in that a tapered part is formed from the upper end portion of the outer pipe, which makes a good appearance when being mounted onto the chair or the chair base and then diversifies the chair design.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a sectional view illustrating a construction of a conventional column unit;

FIG. 1 b is a sectional view illustrating a case when a lateral force is applied to the column unit of FIG. 1 a;

FIG. 2 is a sectional view exemplifying the column unit of a conventional gas cylinder;

FIG. 3 a is a sectional view illustrating a construction of an assembly of a column unit for a chair according to a first embodiment of the present invention;

FIG. 3 b is a sectional view illustrating the assembly of the column unit for the chair in detail according to the first embodiment of the present invention;

FIG. 4 a is a sectional view illustrating a construction of an assembly of a column unit for a chair having a long-type taper according to a second embodiment of the present invention;

FIG. 4 b is a sectional view illustrating the construction of the assembly of the column unit for the chair shown in FIG. 4 a, in which a spindle assembly is removed;

FIG. 4 c is a sectional view illustrating the construction of the assembly of the column unit for the chair shown in FIG. 4 b, in which a spindle guide is removed;

FIG. 4 d is a sectional view illustrating an outer pipe which is a structural element of the assembly of the column unit for the chair shown in FIG. 4 a;

FIG. 5 a is a sectional view illustrating a construction of an assembly of a column unit for a chair having an all-type taper according to a third embodiment of the present invention;

FIG. 5 b is a sectional view illustrating the construction of the assembly of the column unit for the chair shown in FIG. 5 a, in which a spindle assembly is removed;

FIG. 5 c is a sectional view illustrating the construction of the assembly of the column unit for the chair shown in FIG. 5 b, in which a spindle guide is removed;

FIG. 5 d is a sectional view illustrating an outer pipe which is a structural element of the assembly of the column unit for the chair shown in FIG. 5 a, in which an upper end of the outer pipe is curled;

FIG. 6 is a sectional view illustrating an inner pipe of the assembly of the column unit for the chair according to the embodiments of the present invention;

FIG. 7 is a sectional view illustrating an outer pipe of the assembly of the column unit for the chair according to the embodiments of the present invention;

FIG. 8 is a side view illustrating a spindle guide of the assembly of the column unit for the chair according to the embodiments of the present invention;

FIG. 9 is a sectional view illustrating the spindle guide shown in FIG. 8;

FIG. 10 a is a sectional view illustrating an assembly of a column unit for a chair according to a fourth embodiment of the present invention;

FIG. 10 b is a partially enlarged view illustrating a portion ‘A’ of FIG. 10 a; and

FIG. 10 c is a partially enlarged view illustrating a securing part of FIG. 10 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 3 a, a column unit for a chair according to one embodiment of the present invention, like the prior art, may be applied to a gas cylinder having a gas open/close pin 8, a tapered holder 8 a, a valve 8 b and a piston 5 a within a spindle assembly 2. Reference numerals 6, 6 a, and 6 b indicate a piston rod, a cushion rubber, and a bearing assembly, respectively, which are elements provided in a conventional gas cylinder, so detailed descriptions thereof will be omitted.

Meanwhile, as shown in FIG. 3 b, the column unit for the chair includes an outer pipe 10, an inner pipe 20 and a spindle guide 30.

The outer pipe 10, as shown in FIG. 4 d, may include a flat part 16 having a constant length, an inclined part 12 having a gradually increasing diameter toward its end portion, and a linear part H extending from the inclined part 12. Also a securing plate 11 to which an end portion of the piston rod 6 (refer FIG. 3 a) is fixed is provided within the outer pipe 10. A concave engagement jaw 14 is formed along the inner peripheral surface of the outer pipe 10 at its upper end portion. Here, the upper end portion of the engagement jaw 14 forms a bent portion 14 a (refer FIG. 4 d), which serves to prevent the inner pipe 20 from being derailed.

Also, the length of the inclined part 12 of the outer pipe 10 may be varied depending on a user's need. In other words, as shown in FIGS. 4 a to 4 d, it may be provided in the form a long-type taper having a liner part H on its upper end portion, or an all-type taper which is directly inclined from the upper end portion, excluding the linear part H as shown in FIGS. 5 a to 5 d.

The inner pipe 20 is formed in a circular shape and provided with a bent portion 21 which is vertically curved outward at its end portion. The bent portion 21 is seated in the engagement jaw 14 of the outer pipe 10 when assembled. As shown in FIG. 6, an engagement protrusion 22 is obliquely projected inward at the inner end portion of the inner pipe 20. In addition, a plurality of through holes h may be formed at the outer periphery of the bent portion 21. These through holes h serve as a kind of drainage during a painting process of the column unit, which prevents water from remaining in the column unit to prevent the column unit from being rusted.

Meanwhile, the inner pipe 20 may be secured to the outer pipe 10 by being pressed against the outer surface of the outer pipe 10 in a state of being inserted within the outer pipe 10. At this point, the pressed area is illustrated as a compressed part 15. A space 13 is formed between the inclined part 12 of the outer pipe 10 and the outer surface of the inner pipe 20.

The spindle guide 30 includes a head portion 31 and a body portion 32 as shown in FIGS. 8 and 9. The head portion 31 is formed with a mounting end 31 a to be extended outward, and the mounting end 31 a is installed in close contact with the end portions of the outer pipe 10 and the inner pipe 20.

Further, the spindle guide 30 may be made from a synthetic resin through an injection molding and also provided with a plurality of slits 35 to reduce its weight for decreasing manufacturing costs. The body portion 32 may be formed with a plurality of engagement recesses 33 at its end portion, which may be fixedly coupled with the engagement protrusions 22 of the inner pipe 20.

In other words, the engagement protrusion 22 maintains an engagement state within the engagement recesses 33 of the spindle guide 30, so that the spindle guide 30 cannot be derailed outward when being inserted within the inner pipe 20.

In the column unit for the chair in accordance with one embodiment of the present invention as constructed above, the spindle assembly 2 is inserted within the spindle guide 30. At this moment, the inner peripheral surface of the spindle guide 30 and the outer peripheral surface of the spindle assembly 2 maintain a parallel insertion state. Accordingly, even if a load is applied in a lateral direction, i.e., at 360° in any direction with respect to a vertical axis of the column unit, the load will be applied to the entire contact surface between the spindle guide 30 and the spindle assembly 2, which makes it possible to prevent generation of a load concentration in a local area.

The inclined part 12 formed in the outer pipe 10 creates a space 13 between the inner pipe 20 as a cavity to be inserted and seated at a central hole of a chair base, which can minimize loss of materials during a machining process thereof and can be secured to each other by being pressed, thereby improving a production efficiency.

According to the fourth embodiment of the present invention as shown in FIG. 10 a, a substantially ‘Y’ shaped outer pipe 10 is provided, excluding an inner pipe 20. This embodiment has a construction in which a spindle guide 30 is directly installed within the outer pipe 10. At this point, a securing part 18 (refer FIG. 10 c) in an inward curved shape (refer FIG. 10 c) is formed in a peripheral direction at the end portion of the outer pipe 10, which prevents the spindle guide 30 from being moved upward. Further, an engagement step 19 is formed at the outer surface of the spindle guide 30, so that the lateral surface of the spindle guide 30 makes contact with the outer pipe 10 to fix the same, while the outer inclined surface of the spindle guide 30 is in contact with the inner surface of the outer pipe 10 to fix the outer pipe 10. Here, the spindle guide 30 can be coupled with the outer pipe 10 to form a cavity V therebetween. With constructions as such, it can be appreciated that the securing part 18 of the outer pipe 10 is bent to be fixed to a seating part 18 a of the spindle guide 30 without a separate fixing tool.

According to the fourth embodiment of the present invention as described above, it can be noted that by excluding the inner pipe 20 the construction of the device can be simplified, which makes it possible to decrease the manufacturing cost and improve the installation efficiency.

Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

1. A column unit for a chair to adjust a height of the chair by moving a spindle assembly upward or downward within the column unit, the column unit comprising: a cylindrical outer pipe; a piston rod inserted within the outer pipe so as to provide a gas fluid passage of a valve within the outer pipe, the piston rod having an exposed end portion fixed to a bottom surface of the outer pipe; the spindle assembly being moved upward or downward when the gas fluid passage is changed by the piston rod; a spindle guide provided within an upper side of the outer pipe to guide and support an upward or downward movement of the spindle assembly; and an inner pipe inserted within the outer pipe to define a space between an inclined part of the outer pipe and the inner pipe, wherein the outer pipe has a gradually increasing diameter toward an end portion of the outer pipe so that the outer pipe has the inclined part, and the spindle guide is inserted within the inner pipe to guide the upward or downward movement of the spindle assembly.
 2. A column unit for a chair to adjust a height of the chair by moving a spindle assembly upward or downward within the column unit, the column unit comprising: an outer pipe including an inclined part having a gradually increasing diameter toward an end portion of the outer pipe; an inner pipe inserted within the outer pipe; and a spindle guide installed within the inner pipe to guide the upward or downward movement of the spindle assembly.
 3. The column unit for the chair as claimed in claim 1, wherein the outer pipe has a linear part extending by a predetermined length from the inclined part.
 4. The column unit for the chair as claimed in claim 1, wherein the outer pipe has an engagement jaw formed at an inner portion of an end portion of the outer pipe, the end portion of the inner pipe is bent outward and is seated in the engagement jaw, and the outer and inner pipes are secured to each other by pressing their outer surfaces.
 5. The column unit for the chair as claimed in claim 4, wherein the inner pipe is provided with at least one through hole formed along the outer periphery of its end portion.
 6. The column unit for the chair as claimed in claim 1, wherein the inner pipe has an engagement protrusion formed on an inside of the inner pipe, and the spindle guide has an engagement recess formed on an outside of the spindle guide, into which the engagement protrusion is inserted.
 7. A column unit for a chair to adjust a height of the chair by moving a spindle assembly upward or downward within the column unit, the column unit comprising: a cylindrical outer pipe; a piston rod inserted within the outer pipe so as to provide a gas fluid passage of a valve within the outer pipe, the piston rod having an exposed end portion fixed to a bottom surface of the outer pipe; and the spindle assembly being moved upward or downward when the gas fluid passage is changed by the piston rod; a spindle guide provided within an upper side of the outer pipe to guide and support an upward or downward movement of the spindle assembly, wherein the outer pipe has a gradually increasing diameter toward an end portion of the outer pipe so that the outer pipe has the inclined part, and the outer pipe is integrally formed with a securing part being curved at its end portion to encompass the end outer peripheral surface of the spindle guide.
 8. The column unit for the chair as claimed in claim 7, wherein the spindle guide has at least one engagement step formed on an outer peripheral surface of the spindle guide.
 9. The column unit for the chair as claimed in claim 7, wherein the spindle guide has a seating part circumferentially formed at an upper end portion of the spindle guide, the securing part of the outer pipe being seated in the seating part and the seating part being fixed to the securing part while being engaged with the securing part. 